Digital Signal Processing (DSP) technology is indispensible for modern auditory research. Real-time signal processing is essential for speech processors for cochlear implants, hearing aids, and sensory substitution devices. Electrophysiology (ABR) and otoacoustic emissions (OAE) research requires real-time processing for research on techniques that are outside the realm of commercial ABR and OAE devices, or for portable test equipment. Biological assays of dynamic processes may require real-time image processing to differentiate cellular mechanisms on millisecond time scales. DSP hardware and software are complex and rapidly evolving technologies that require higher-level engineering resources than can usually be justified by any one research application. This Engineering Core proposal would support the engineering expertise necessary to develop, maintain, and integrate DSP technology into the existing research projects at HEI. This core proposes two levels of engineering support: specialized DSP expertise and general engineering services. Specific Aim 1 will develop and maintain DSP expertise on the latest hardware and software platforms. The Engineering core will develop core DSP hardware platforms with associated software operating systems, which will allow investigators to download programs into the DSP platform from PC or MAC-based laboratory machines and control data flow and handle errors from the DSP system. Specific Aim 2 will allow Engineering Core personnel to interface with project-specific engineers to develop specialized hardware and software for input sensors and output actuators for the individual projects. Sensors might include vibratory, acoustic, photonic, biosensors, or electrical. Actuators could include acoustic, vibratory, electrical, or digital implant transmission codes. Specific Aim 3 will provide Core Investigators with Engineering support for standard acoustic test equipment, such as audiometers, commercial ABR and OAE measurement equipment, and psychophysical test equipment. The Engineering Core will provide assistance in configuring, maintaining and calibrating such equipment.